Electrode catheters have been in common use in medical practice for many years. They are used to stimulate and map electrical activity in the heart and to ablate sites of aberrant electrical activity. Atrial fibrillation is a common sustained cardiac arrhythmia and a major cause of stroke. This condition is perpetuated by reentrant wavelets propagating in an abnormal atrial-tissue substrate. Various approaches have been developed to interrupt wavelets, including surgical or catheter-mediated atriotomy. Prior to treating the condition, one has to first determine the location of the wavelets. Various techniques have been proposed for making such a determination, including the use of catheters adapted to measure activity within the heart.
In use, the electrode catheter is inserted into a major vein or artery, e.g., femoral artery, and guided into a chamber of the heart. Within the chamber, the catheter is maneuvered through movements that include deflection of a distal portion of the catheter so that the tip electrode is positioned at a target location on the heart wall in the heart chamber for mapping and/or ablation. The ability to control the exact position and orientation of the catheter is critical and largely determines how useful the catheter is.
Accordingly, a desire exists for a catheter that can provide more variations in deflection curvature, especially in different sections along the catheter. A desire also exists for a catheter that can provide a pre-deflection such that manipulation of the control handle increases the curvature of the pre-deflection along with the remainder of the catheter. Such a catheter should provide a control handle by which multiple deflections can be controlled by a single movement.